Aalenian-Bajocian belemnites from the Middle and High Atlas, Morocco: taxonomy, biostratigraphy and palaeobiogeographical affinities
Authors: Robert Weis 1, Driss Sadki 2 & Nino Mariotti 3
1 National Museum of Natural History, Luxembourg
2 University Moulay Ismaïl, Meknès, Morocco
3 Sapienza University, Rome
Source: Weis, R., D. Sadki & N. Mariotti, 2017. – Aalenian-Bajocian belemnites from the Middle and High Atlas, Morocco: taxonomy, biostratigraphy and palaeobiogeographical affinities. – Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen Band 284 Heft 2 (2017): 215 – 240. – DOI: 10.1127/njgpa/2017/0659
Abstract: The early Middle Jurassic represents an interval of important taxonomic diversification in belemnites in the Western Tethys. Field work in the Moroccan Atlas mountains has permitted to collect numerous belemnite rostra, ranging from the uppermost Aalenian (Concavum Zone) to the lower Bajocian (Propinquans Zone). Seven species belonging to the genera Holcobelus, Calabribelus, Belemnopsis, Conobelemnopsis and ?Dicoelites (all suborder Belemnopseina) are described for the first time from the Middle Atlas (area of Boulemane) and the Central High Atlas (area of Rich). The taxonomic composition of the genus Calabribelus is re-discussed in the light of the new findings, including the description of C. combemoreli sp. nov. The taxonomic analysis evidences strong affinities with Belemnopseina-dominated faunas from the French Subalpine Basin (SE France) and Calabria (South Italy). These Mediterranean assemblages strongly differ in taxonomic composition from coeval boreal belemnite faunas of NW Europe, characterized by a predominance of the suborder Belemnitina. The new records from Morocco confirm that during the late Aalenian and early Bajocian faunal segregation between Mediterranean (Tethyan domain) and Euro-Boreal (Boreal domain) assemblages is fully expressed, for the first time in the evolutionary history of belemnites.